Sunflower (Asteraceae): General Blooming Period, Daily Peak Blooming Time, and Sowing Period

The sunflower is an annual herbaceous plant of the genus Helianthus in the family Asteraceae. It is cultivated throughout China. Sunflower seeds are called sunflower seeds (kuihua zi), and are often eaten as a snack after being roasted. So when does the sunflower generally bloom? At what time of day does it bloom the most? And when is the best time to sow it? The details are compiled below:

Sunflower blooming time

Sunflowers are generally sown in April, with the blooming period from July to August, the seed maturity period from August to September, and the flowers mostly opening between 4 and 6 in the morning.

Sunflowers can be grown in all four seasons, mainly in summer and winter. The blooming period can last more than two weeks. Besides its appearance resembling the sun, the sunflower's blooms are bright and generous, making it suitable for ornamental display, and its seeds have even greater economic value: they can be made into the popular sunflower seeds (kuagua zi), and can also be pressed into a low-cholesterol, premium edible sunflower oil. Sunflower varieties can be divided into “general ornamental” varieties or “edible” varieties. General ornamental varieties are characterized by a shorter, smaller plant, usually not exceeding half a meter, and are therefore suitable for growing in pots; edible varieties are taller and larger, planted in ordinary open-field nursery soil, and can grow to more than 2 meters. Sunflowers grow quite rapidly, usually blooming about two months after planting; their flower forms are divided into single-petaled, double-petaled, or single-flowered and multi-flowered, and the blooming period is quite long, reaching more than two weeks.

Sunflowers are not demanding about soil and can grow in all kinds of soil, from fertile soil to dry land, poor thin soil and saline-alkali land. They have a relatively strong tolerance for saline-alkali conditions.

In which month are sunflowers generally sown

How to grow sunflowers

Part One: Seeds

To raise seeds, first soak them in warm water, then plant them in the soil with the pointed tip of the seed facing down; they will sprout in about 4 to 5 days.

Part Two: Sowing

1. Sowing time: sowing can be done when the soil temperature at a depth of 125px reaches 5°C. The basic principles for choosing the sowing time are: first, according to the patterns of salinization, sow appropriately early or late so that the seedlings avoid saline-alkali damage; second, carry out spring sowing or summer sowing according to the growth period of the variety; third, adjust the sowing time according to the patterns of disease occurrence so as to avoid the season when diseases are frequent; fourth, adjust the sowing time according to growth characteristics so that the blooming and grain-filling period avoids high temperatures above 28°C.

2. The germination rate and seedling emergence rate of confectionery sunflower are lower than those of oilseed sunflower, and its ability to push through the soil is also inferior to that of oilseed sunflower. To ensure the number of emerged seedlings, the actual sowing amount should be increased by 10—20% over the calculated sowing amount. Confectionery sunflower has a very strong self-regulating ability: with high planting density, the flower head is small and the seeds are small; with low density, the flower head is large and the seeds are also large. On the premise of ensuring both yield and marketability, the number of plants kept per 667 sq m should preferably be maintained at around 3000 plants, with a row spacing of 60—1750px and a plant spacing of 30—875px. The sowing amount is determined according to the characteristics of the variety and the cultivation requirements. Generally, manual dibbling requires 600 grams of seed per 667 sq m, and machine sowing requires 700 grams of seed.

3. Seed fertilizer: confectionery sunflower has a relatively long growth period and tall plants. The seed fertilizer amount is 5—8 kg of diammonium phosphate per 667 sq m applied in holes or in bands, or 10 kg of triple superphosphate.

4. Sowing method: at sowing time the soil moisture should be good, and the depth should preferably be 3—100px. The sowing methods used are:

① Make beds manually or by machine, and dibble or drill in furrows;

② Precision dibbling, with 1—2 seeds per hole. In arid areas, the method of deep furrowing and shallow covering can be adopted, sowing the seeds on moist soil with good moisture content.

Part Three: Sowing Conditions

Sunflower sowing time: March to April.

Suitable temperature for sowing: 18 to 25°C.

Sprouting time: 5 to 7 days.

Sowing method: dibbling, covering with about 25px of soil; after sowing, blooming occurs in about 50 to 80 days, with slight differences in each detail depending on the variety. Adverse symptoms.

Part Four: Field Management

Field management is an important step for cultivating robust plants and achieving high quality and high yield. As the saying goes: “Three parts planting, seven parts management.”

1. Inspect the field and fill in missing plants. The sunflower is a dicotyledonous crop, and pushing through the soil to emerge is rather laborious; in addition, poor land preparation, poor sowing quality, or surface soil crusting after rain following sowing, or damage by diseases, insects, rodents, birds and the like, can all easily cause missing plants and broken rows. To ensure full emergence after sowing, the field must be inspected row by row during the emergence period; if plants are missing in patches or rows, reseeding must be done promptly, soaking the seeds to sprout until they show white and then reseeding promptly. Where few plants are missing, thin plants should be moved to fill gaps, transplanting with soil attached (paying attention to the seedlings' orientation toward the sun), and watering well after transplanting to set the roots; the survival rate can generally reach more than 95%. A portion of backup seedlings can also be raised to ensure the need for a full stand.